CVE-2017-5641 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in org.apache.flex.blazeds:flex-messaging-core. 2 public exploit references exist, so weaponization risk is real. A fix is available for org.apache.flex.blazeds:flex-messaging-core — see the affected versions and patch details below.
Apache Flex BlazeDS unsafe deserialization
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2017-5641 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.flex.blazeds:flex-messaging-core☕org.apache.flex.blazeds:flex-messaging-remotingReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
Previous versions of Apache Flex BlazeDS (4.7.2 and earlier) did not restrict which types were allowed for AMF(X) object deserialization by default. During the deserialization process code is executed that for several known types has undesired side-effects. Other, unknown types may also exhibit such behaviors. One vector in the Java standard library exists that allows an attacker to trigger possibly further exploitable Java deserialization of untrusted data. Other known vectors in third party libraries can be used to trigger remote code execution.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.flex.blazeds:flex-messaging-core | all versions | 4.7.3org.apache.flex.blazeds:flex-messaging-core:4.7.3 |
| ☕Maven | org.apache.flex.blazeds:flex-messaging-remoting | all versions | 4.7.3org.apache.flex.blazeds:flex-messaging-remoting:4.7.3 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.flex.blazeds:flex-messaging-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.flex.blazeds:flex-messaging-core to 4.7.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2017-5641 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2017-5641 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2017-5641. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2017-5641 in your dependencies?
O3 Security finds CVE-2017-5641 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.